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Intracellular expression and serum levels of eosinophil peroxidase (EPO) and eosinophil cationic protein in asthmatic children
Author(s) -
Norbert Krug,
Ute Napp,
I. Enander,
Elisabeth Eklund,
Christian Rieger,
U. Schauer
Publication year - 1999
Publication title -
clinical and experimental allergy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.462
H-Index - 154
eISSN - 1365-2222
pISSN - 0954-7894
DOI - 10.1046/j.1365-2222.1999.00680.x
Subject(s) - eosinophil cationic protein , eosinophil peroxidase , eosinophil , intracellular , immunology , peroxidase , major basic protein , medicine , asthma , biology , enzyme , biochemistry
Background Eosinophils are involved in the chronic inflammatory response in asthma and their basic proteins are thought to play a major pathophysiological role in this process. While serum levels of basic proteins have been used to monitor the ongoing allergic disease, little is known about the intracellular expression of these proteins in clinical situations. Objective The aim of the study was to determine the intracellular expression of eosinophil cationic protein (ECP) and eosinophil peroxidase (EPO) in asthmatic children and control subjects and relate it to serum levels of both proteins,lung function tests and immunoglobulin (Ig)E levels. Methods Serum ECP and EPO concentrations were determined by immunoassays in 13 asthmatic children (mean age: 9 ± 1 years, mean FEV 1 : 92 ± 10% predicted, geometric mean PC 20 histamine 0.5 mg/mL) and 10 age‐matched, healthy control subjects. A flow cytometric single cell assay was employed to detect intracellular ECP and EPO in peripheral blood eosinophils. Results While serum concentrations of both ECP (asthma: median 15.0 μg/L [range 3.6–57.7] vs control: 5.9 μg/L [2.7–9.1]; P = 0.02) and EPO (22.9 μg/L [5.2–82.5] vs 7.2 μg/L [2.5–12.7]; P = 0.008) were significantly elevated in asthmatics, the intracellular expression of ECP and EPO (measured as mean fluorescence intensity) was decreased (EG 1 : 55.3 [17.7–120.8] vs 100.3 [46.5–264.4]; P = 0.01; EG 2 : 80.2 [24.1–135.3] vs 133.7 [32.1–244.9]; P = 0.04 and EPO: 49.7 [23.1–155.8] vs 94.9 [28.8–115.2]; P = 0.03). In asthmatics there was a significant correlation of FEV 1 with intracellular ECP and of bronchial hyperresponsiveness with serum EPO and ECP. Furthermore, total IgE levels were positively correlated with serum EPO only. Conclusion We conclude that in asthmatics the intracellular content of ECP and EPO in peripheral eosinophils is reduced possibly due to degranulation. Epitope masking in activated eosinophils or a shift to early bone marrow‐derived progenitors with less granule proteins are further possible explanations.